The Signature Database Root Node (SigDBRoot) is a list of Signatures. All signatures have the property ElemID and contain a list of Descriptors and a List of Classes.
The property ElemID identifies a Signature.
Additionally, all signatures have a list of Descriptors that is stored in the node <DescibingElems>.
All signatures have another list of classes that is stored in contained in the node <Classes>, this list contains usually also all classes of the Descriptors in the DescibingElems node.
An example for a Signature contained in a SigDBRoot:
<SigDBRoot>
<Signature ElemID="1023">
<DescibingElems>
<ColorClass ColorName="black" ElemID="1024">
<Class ClassName="black" ElemID="1025" />
</ColorClass>
</DescibingElems>
<Classes>
<Class ClassName="black" ElemID="1025" />
<Class ClassName="Jug" ElemID="1026" />
</Classes>
</Signature>
</SigDBRoot>
see also <SignatureDB>